A review of design considerations and performance enhancement techniques for thermocline thermal energy storage systems

Thermal energy storage systems play a fundamental role in the storage of renewable energy and in the recovery of useful heat generated from various systems. As an efficient and low-cost thermal energy storage technology, thermocline system has gained more and more attentions. In this paper, a system analysis on the published literatures in recent ten years was first made and then divided them into five aspects including structure design and optimization, material selection and application, control strategies in reducing thermocline degradation, integration of thermocline system in energy system, and numerical simulation of thermocline. Depending upon the reported research directions. Moreover, introduction for each research aspect was provided with the emphasis on the optimization of the system thermal performance. In addition, based on these summarizations, authors pointed out that all the above five aspects have significant influences on the performance of the thermocline system, in which both structural optimization and material selection are regarded as recent research hot points. Finally, recommendations a prospect was given on future research trends and potential application technologies of the thermocline technology. All the endeavor made in this paper is to provide a comprehensive and detailed information and possible technique challenges on thermocline system for the researchers all over the world with an objective of further promoting the research in this area.